Power converters commonly used in optical networks convert AC or DC input power to DC output(s) frequently have multiple outputs that are often derived from multiple transformers within the converters. In converters employing multiple transformers, DC power is commonly derived as a first stage converts commercial AC power into DC power by using an AC/DC converter. Once converted, the power is manipulated in a second stage by a DC/DC converter. This secondary conversion further conditions the power resulting in multiple voltage outputs. Such outputs commonly include voltage values of +5 V, +3.3 V, -48 V and a variable return voltage.
Additionally, typical power converters include a battery backup stage that operates as an alternate power source when commercial AC power fails. The battery is coupled to both the AC/DC stage and the DC/DC stage. During normal operation, when commercial AC power is online, the battery operates in a charging mode, where the AC/DC converter supplies power to maintain the charge. When AC power fails, the battery switches to a discharge mode to supply power to the optical network.
A major disadvantage to such a power converter is the conversion inefficiencies encountered. When power is converted, whether AC/DC or DC/DC, inefficiencies arise to reduce the quality of the output. Where two converters are employed, the conversion inefficiencies are compounded, resulting in unacceptable power loss.
To combat this problem, some power converters partially bypass the second conversion stage. In cases where the -48 V output is highly loaded, this voltage is supplied directly from the AC/DC converter in the first stage when commercial AC power is available. As with the previous converter, when commercial AC power fails, the -48 V is supplied to the output from the battery by way of the third stage DC/DC converter. While this configuration allows only one converter to be used at any time for the -48 V output, unacceptable inefficiencies still exist for the remaining outputs.
Finally, another major disadvantage to either of the configurations shown relates to costs associated with employing a DC/DC converter in the second stage. The addition of an supplementary transformer in the system (i.e., in the DC/DC converter) greatly increases the costs in building and maintaining this system. Unfortunately, such a converter is necessary to ensure properly conditioned voltages at the various outputs.
Accordingly, what is needed in the art is a power supply and a method of supplying power that employs a single transformer capable of overcoming the above-described deficiencies.